rotor alternative?

[Paul Rubin]

aaron at reportlab.com (Aaron Watters) writes:
> > Is an alternative to rotor planned?

> Dunno, but I've been using this in my own experimental
> development (private key, synchronous communication).
> 
> http://athos.rutgers.edu/~aaron/python/pulver.py
> 
> I don't know how strong it is, but I rashly guess that
> it might be pretty strong.

At first glance that function looks awful (no offense intended), and
the implementation looks very slow.  I'd strongly advise against doing
anything serious with it.  If you want a pure-Python cipher, please try

  http://www.nightsong.com/phr/crypto/p3.py

which uses the library SHA function to generate the keystream for a
stream cipher.  It's been vetted by the sci.crypt crowd and should be
quite strong unless I did something silly.

See

  http://www.nightsong.com/phr/crypto/blockcipher.tgz

for a proposed new block cipher API which supports the standard FIPS
modes of operation.  A reference Python implementation is included in
the tarball but is too slow for production use.  I put it aside when
the machine I was writing it on suffered a disk crash, but I ought to
get back to it.  My hope is that this module will be added to the
standard Python library once it's done.